In mines, the mine roof is ordinarily supported with roof bolts which are inserted into long holes drilled with a drill auger. These roof bolts are provided at their bottoms with plates that are held tight against the roof surface by a bolthead or nut. In some instances, a roof bolt is secured in place at its upper end by means of an expansible device threaded onto the upper end of the bolt. This is caused to expand upon rotation of the roof bolt and engage the sides of the drill hole where the roof bolt is located. However, instead of using an expansible member at the upper end of the roof bolt, it is also possible to secure the roof bolt within a drilled hole by means of a resin. When a roof bolt is secured in place by means of a resin, a frangible cartridge containing a synthetic resin-based composition is first inserted into a hole drilled into the mine roof for reception of the roof bolt. The frangible cartridge is destroyed by rotating the roof bolt in the hole while in contact with the cartridge so as to cause the contents of the cartridge to be mixed and displaced into the annular space between the roof bolt and the wall of the drilled hole. Curing of the synthetic resin takes place in situ with the result that the roof bolt, which carries a plate at its lower end, is secured within the hole.
In the past, it has been more or less common to manually insert resin-secured roof bolts in place. That is, the drilling operation is performed by a rotation unit attached to one end of a boom arm carried on a rubber-wheeled carriage or the like. The rotation unit rotatably supports a drill bit which is forced upwardly into the mine roof as it is rotated. Once the hole is drilled, an operator manually inserts resin tubes up into the hole. Thereafter, the operator replaces the drill bit with a roof bolt on the rotation unit; and the roof bolt is then driven up into the hole such that it punctures the frangible resin cartridge to permit the resin to cure and hold the roof bolt in place.
One disadvantage of the prior art roof bolting operation described above is the necessity for the machine operator to perform various roof-bolting operations immediately beneath an unsecured portion of the mine roof. Until the roof bolt is inserted into the drilled hole and secured in place, it is possible for a portion of the mine roof to drop and cause injury to the roof bolt operator. Furthermore, an operation of this type requires a great deal of manual labor and is slow and cumbersome.